I'm pretty new with Yii. I was trying to generate some sample Modules with Gii. After Gii finished I got an error on the generated code, when I checked that I saw this:

class DefaultController extends Controller

As I said I'm not expert, but as far as I read all the Yii classes should start with a capital "C" letter to avoid the conflicts with user defined classes. So, I just changed the "Controller" to "CController" and the error gone!

I'm not sure, maybe there are differences between Modules and other things in Yii, but otherwise it looks like a bug.